1. Field of the Invention
The present invention relates generally to electrical apparatus and, more particularly, to a racking device for manipulating an electrical switching apparatus, such as a circuit breaker. The invention also relates to a power module for a racking device.
2. Background Information
Electrical switching apparatus, such as relatively large circuit breakers, are commonly disposed in an enclosure or housing structure having a plurality of compartments or sections. The circuit breakers may be stacked, as shown in FIG. 1, or they may be disposed in any other suitable configuration within the housing structure. Large circuit breakers are typically heavy, often weighing as much as 1000 lbs. or more. Therefore, in order to facilitate the manipulation (e.g., insertion, removal, adjustment, or any other movement) of the circuit breaker, it is usually necessary to employ a moving device commonly referred to as an extraction or racking device.
FIG. 1 shows an example of a racking device 2 comprising a frame 4 including a bucket 6 for supporting the electrical apparatus (e.g., circuit breaker 8) being manipulated. A drive gear 10 is used to move the bucket 6 vertically along a pair of guide rails 12 (only one rail 12 is shown), and a set of trucks or wheels 14 are disposed on an elongated base 5 for moving the entire racking device 2 toward and away from the housing structure 16. By way of example, in operation, the racking device 2 is generally placed in front of the housing structure 16 with the guide rails 12 being aligned with the vertical sides of the housing structure 16. Brakes (not shown in FIG. 1) on each wheel 14 are then set in order to lock the wheels 14. The circuit breaker 8, which typically has a pair of roller wheels 18, is then rolled out of the housing structure 16 onto the bucket 6 of the racking device 2. Once the circuit breaker 8 is on the racking device 2, the brakes are released to remove the circuit breaker 8. Installation of a circuit breaker 8 follows essentially the same procedure, except in reverse. Other circuit breaker manipulations, such as shuffling the position of one or more circuit breakers within the housing structure 16, can also be accomplished using the vertical movement capabilities of the racking device 2.
Racking devices of this nature suffer from a number of disadvantages. Among them is the fact that the racking device 2 is generally bulky and awkward to manipulate. Specifically, the base 5 of the frame 4 of the racking device 2 extends from the guide rails 12 a relatively far lateral distance thereby making the device base 5 unnecessarily large and difficult to transport and maneuver and align with respect to the housing structure 16. The bucket 6 is also generally heavy and difficult to adjust vertically. There is, therefore, a need for a smaller, more compact and maneuverable racking device.
Additionally, conventionally, an operator performing the circuit breaker manipulation has been required to be in physical proximity with the racking device 2. Therefore, the operators are typically required to wear approved personal protection equipment (PPE) to resist serious injury that could result if an electrical failure were to occur during the racking process. However, PPE is generally bulky, hot and uncomfortable which dissuades operators from wearing it. An alternative solution is desired. There is, therefore, also a need for a racking device which may be remotely operated.
U.S. Patent Application Pub. No. 2003/0200648 is an example of one attempt to provide a remote power racking system. Like the racking device 2 of FIG. 1, the disclosed racking apparatus includes a frame forming a large base and a pair of guide rails extending upwardly from the base. Also included are an electric motor having a shaft, an adaptor arranged to be coupled to an industrial circuit breaker, and an actuating assembly which provides vertical movement of the motor. A controller is carried by the frame for controlling the motor and the actuating structure and a control station is operatively associated with the controller in order to operate the controller from a remote location. However, not only are the frame and the base portion thereof large and difficult to maneuver, but the system is also complex. For example, vertical movement of the motor actuating assembly requires the combination of multiple components including at least a chain, sprockets, a second motor, and a piston and actuator, in order to provide vertical movement of the motor on the frame guide rails. The motor and shaft assembly are also relatively heavy, making manual vertical adjustment of the device very difficult for the operator. The associated method of operating the racking apparatus is also complex. Specifically, among the requirements of the disclosed racking apparatus is that it relies upon a torque profiler, for example, which is dependent upon the exact type of circuit breaker and its location (e.g. cell) on the rack in order to profile torque over the entire range of movement of a racking operation. There is, therefore, a further need for a simplified racking device and method which are universally compatible with a wide variety of circuit breakers.
In summary, there is a need for a racking device that is easy and quick to set-up, is portable and easy to maneuver, is compatible with numerous circuit breaker models, is remotely operable, and which requires minimal programming.
There is, therefore, room for improvement in racking devices and in power modules for racking devices.